The appearance of the great range of brightness among stars is du ;jgtn-ey,5b nz.0xgr j7d;mg e to

  The absolute luminosity for mop5,x7dzbjcc 5 st stars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yellos7n5 7 ys3t b,lcgemz6rcbw( )w. What is 3 sty)l rc 6esc7bbzmng,( 7w5their rank from coolest to hottest?

  A Hertzsprung-Russell dh9junn +zlu8 otr ;,8hiagram shows stars on a plot of

  A white dwarf star withob . 6klds;xg1 a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a 8d + nrb42ml; cjsgc z.zac:c5star will collapse into a white dwarf) is, if the mass of our Sun isc+;ac z4n2.mjs:bld 8cr z 5cg M, about

  Supernovas are thought to alwaczz;atz-vg . p4rk+n* ys result in

  Black holes

  Pulsars are rapidly se:nz9h3ma 1am4y- bnd; gj pm3pinning

State Einstein's principle of el v:ghy,*7 zcjx.ei,iqn l9+aquivalence.

  The Schwarzschild radius of an5cg5 m8fyb p( black hole is that radial distance from the center of a sphere within which not evfb5(y5g8m cpn en light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general relativity theory. It can be calculated from a star's mass M as: $R = 2GM/c^2$. Take the radius of both stars A and B as the Schwarzschild radius. If the mass of star A is twice as much as the mass of star B, the average density of star A, compared to star B will be

  When a distant source emits light of a particul 9d:+x.vxhg4vl;ogv wrg1 4aear wavelength in the visible, and the source is moving away from us, the color of the light appears to us to bexvvo d41lgxgw r;9 gh4eva+ .: shifted toward the

  The cosmic background radiation correspondjuaa: t8ta 7r+kw.mx6ex)c4wj ogn5* s to a temperature of about

  The Sun has apparent brx7wt lhe9ly, 0mrr;wgu;lu, 8 ightness at Earth ($1.5 \times 10^{8} \; km$ away) of B. What would be the apparent brightness of the Sun at Pluto, which is $6.0 \times 10^{9} \; km$ from the Sun?

  A star has absolute luminosity equal to that of to hd5 zfp*:x 0q.o2zd g13 c)cihpack1he Sun ($1.5 \times 10^{8} \; km$ from the Earth) but is 10 pc away from the Earth. By what factor will it appear dimmer than the Sun?

  The Earth's orbit has a mej y2lea k.-o mgl/dczpot,gzr(/3,( nan radius of $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in km?

  The Earth's orbit has a mean8z ;.umjdqnd ; radius of $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for x8jqr 3/i xfda+o,y:pProxima Centauri, which is Earth's nearest star at 3+ /jpfx xdy,:arq8io4.3 ly?

  The apparent brightness of a z*it( 9b0f drtstar is $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approxinq t+t3u839qwe f t1pz)hxm8umate age of the universe is 1/H, where H is the Hubble constant. t8mtwu83 q1ft+z3h)upne 9qx Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at sqyq7i9vq s 1/4j1qevckg .yn 2o *-uq1.0% of the speed of light, how far away is it fro qqi-vnoq cy7yv1qgs /29que4jk.s1 *m us?

  Estimate the speed o f:m h xdrlou6xl+758cf a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a ) s5vx awg8d1l5fa(opstar which is 100)o(x av1wspfgd8l55a million light-years from us.

  About 1 ms after the Big Bang, the temperature of ub ,ndj*/gzy/the universe was about 1013 K. What energy (in enbuz* /,gj /ydV) does this correspond to?